1. Technical Field
The embodiments herein relate to a semiconductor memory apparatus, and more particularly, an output driver configured to output a data signal from a semiconductor memory apparatus.
2. Related Art
An output driver of a conventional semiconductor memory apparatus outputs data and transmits the data to another external chip. A conventional output driver is generally composed of a pull-up driver and a pull-down driver. A conventional pull-up driver includes a plurality of PMOS transistors that each receives a pull-up signal to adjust current driving capability, i.e. pull-up capability of an output terminal. The pull-up signal is then transmitted to the PMOS transistors through metal options. Therefore, the pull-up capability of the pull-up driver is adjusted by turning on/off the metal options.
A conventional pull-down driver includes a plurality of NMOS transistors that each receives a pull-down signal to adjust current driving capability, i.e. pull-down capability of the output terminal. The pull-down signal is transmitted to the NMOS transistors through a metal option. Therefore, the pull-down capability of the pull-down driver is adjusted by turning on/off the metal options.
A conventional output driver fixes the pull-up capability and the pull-down capability by determining whether to turn on/off the metal options in a wafer state. When the semiconductor memory apparatus is tested after being packaged, the pull-up and pull-down capability of the output driver that is fixed in the wafer state may be changed due to changes in P. V. T (process, voltage, temperature). However, as the pull-up and pull-down capability of the output driver is changed after being packaged, the design of the semiconductor memory apparatus should be changed through revision, which requires a large amount of time and money.